Flow forming connection of metallic parts and resultant part assembly

ABSTRACT

A method and apparatus ( 10 ) provide a flow formed part assembly ( 12 ) having mechanically interlocked first and second metallic parts ( 22 ) and ( 24 ).

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a method and apparatus for mechanically connecting metallic parts to each other by flow forming and also relates to the resultant part assembly.

2. Background Art

Metallic parts utilized in torque transmission such as vehicle transmissions, transfer cases, couplings and other torque transmitting assemblies have previously been made as individual parts by flow forming which involves rotating a part around a central axis about which one or more rotary flow forming tools are rotated and moved axially to form the part about a central mandrel.

Prior art references noted during an investigation conducted in accordance with the present invention include U.S. Pat. Nos.: 2,707,823 Sowter; 2,707,824 Sowter; 2,894,323 Sowter et al.; 2,926,030 Rozmus et al.; and 3,090,116 Burgess.

SUMMARY OF THE INVENTION

One object of the present invention is to provide an improved method for mechanically connecting metallic parts to each other.

In carrying out the above object, the method for mechanically connecting metallic parts to each other in accordance with the invention is performed by rotating first and second metallic parts with each other about a central axis with the first metallic part having an outer locking formation. A flow forming tool is rotated about a tool axis at a location spaced radially outward from the central axis, and the rotating flow forming tool is moved axially along the central axis to flow form the second metallic part around the first metallic part in a mechanically interlocking relationship with the outer locking formation of the first metallic part.

The outer locking formation of the first mechanical part as disclosed includes circumferentially spaced locking projections about which the second metallic part is flow formed to provide both circumferential and axial mechanical interlocking of the parts to each other.

The first and second metallic parts may be made of different types of metals, have different heat treatments, have different compositions, have blanks made by different processes or combinations of the former.

A plurality of flow forming tools may be rotated about associated axes that are spaced radially outward from the central axis, and the rotating flow forming tools are moved together axially along the central axis to provide the flow forming of the second metallic part around the first metallic part in its mechanically interlocking relationship with the outer locking formation of the first metallic part.

Another object of the present invention is to provide improved apparatus for mechanically connecting metallic parts to each other.

In carrying out the immediately preceding object, the apparatus for mechanically connecting metallic parts to each other in accordance with the invention includes a spindle for rotatably mounting first and second metallic parts about a central axis with the first metallic part having an outer locking formation. A flow former includes at least one rotary flow forming tool mounted for rotation about a tool axis at a location spaced radially outward from the central axis. The flow forming tool is mounted for axial movement along the central axis during the rotation thereof to flow form the second metallic part around the first metallic part in a mechanically interlocking relationship with the outer locking formation of the first metallic part.

The spindle of the apparatus includes a mandrel and a tailstock between which the first and second metallic parts are axially clamped and supported for the rotation about the central axis.

The apparatus may be constructed with the flow former including a plurality of flow forming tools that are rotated about associated axes spaced radially outward from the central axis and that are moved axially along the central axis to provide the flow forming of the second metallic part around the first metallic part.

Another object of the present invention is to provide an improved metallic part assembly.

In carrying out the immediately preceding object, the metallic part assembly of the invention includes a first metallic part that has a central axis and an outer locking formation including locking projections extending outwardly from and spaced about the central axis. A second metallic part of the assembly is flow formed around the outer locking formation of the first metallic part and located on opposite axial sides and circumferentially between the locking projections so as to mechanically interlock the first and second metallic parts to each other.

The first and second metallic parts may be made of different metals, have different heat treatments, have different compositions, start with blanks made by different processes, or have combinations of the former.

The objects, features and advantages of the present invention are readily apparent from the following detailed description of the preferred embodiment for carrying out the invention when taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view taken through apparatus of the invention for providing the metallic part connecting method thereof and the resultant metallic part assembly of the invention.

FIG. 2 is an axial view taken along the direction of line 2-2 in FIG. 1 to illustrate a first metallic part that is connected to a second metallic part by the apparatus and method.

FIG. 3 is a sectional view taken along the direction of line 2-2 to further illustrate the construction of the first metallic part.

FIG. 4 is a half sectional view illustrating the manner in which the second metallic part is flow formed around the first metallic part illustrated in FIGS. 2 and 3 to provide the metallic part assembly of the invention.

FIG. 5 is a partial axial view taken along the direction of line 5-5 in FIG. 4 to further illustrate the construction of the metallic part assembly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to FIG. 1 of the drawings, apparatus 10 for providing metallic part connection in accordance with the invention is utilized to perform the method thereof which provides the resultant metallic part assembly 12 shown in FIGS. 4 and 5. The metallic part connecting method, the apparatus 10 and the resultant metallic part assembly 12 will all be described in an integrated manner to facilitate an understanding of all aspects of the invention.

As shown in FIG. 1, the apparatus 10 includes a spindle 14 rotatable about a central axis A. The spindle 14 includes a headstock 16 that mounts a mandrel 18 and also includes a tailstock 20. First and second metallic parts 22 and 24 are mounted by the spindle 14 by axial clamping between the mandrel 18 and tailstock 20. Rotation of the spindle 14 thus rotates the first and second metallic parts 22 and 24 about the central axis A.

The first metallic part 22 as shown in FIGS. 2 and 3 has a generally annular shape and includes an outer locking formation 26 extending about the central axis A and provided by circumferentially spaced locking projections 28 that project radially in an outward direction. These locking projections 28 may be formed as gear teeth, splines or other projections such as between grooves formed in the inner metallic part.

As shown in FIG. 1, the apparatus also includes a flow former 30 that includes at least one flow forming tool 32. As actually shown, there are a plurality of such tools, most preferably three such tools spaced at 120 degrees from each other. Each flow forming tool 32 rotates about an associated axis a and is located outwardly from the central axis A adjacent the outer extremity of the mandrel 18. During the rotation of the first and second metallic parts 22 and 24 on the spindle 14 as described above, the rotating flow forming tools 32 are moved axially along the central axis as shown by arrows b to provide flow forming of the second metallic part 24 over the outer locking formation 26 of the first metallic part 22. This flow forming mechanically interlocks the first and second parts 22 and 24 to each other to thereby provide the part assembly 12 illustrated in FIGS. 4 and 5.

More specifically as shown in FIGS. 4 and 5, the second metallic part 24 has portions 24′ and 24″ that are located on axial opposite axial sides of the outer locking formation projections 28 (FIG. 4) of the first metallic part 22 and has radially inwardly extending portions 34 (FIG. 5) that are located circumferentially between the outer locking formation projections 28. Thus, both axial and circumferential innerconnection of the metallic parts to each other secures their fixed relationship to each other.

The first and second metallic parts 22 and 24 may be made from different types of metals such as steel, zinc, aluminum, etc., may have different heat treatments to provide the required properties for each part, may have different compositions to also provide the required properties for each part, may be formed from blanks made by different processes such as rolling, casting, forming and machining, and may be combinations of the former.

As shown in FIGS. 2 and 3, the first metallic part 22 is initially formed inward of its outer locking formation 26 to provide connection formations 34 which are illustrated as holes that may be machined or otherwise initially formed upon the manufacture of the part. Such connection formations can be more easily provided such as by machining before the flow form connection of the parts to each other as the part assembly. Often, the resultant part assembly construction cannot be provided by a unitary metallic component because the connection formations cannot be machined or otherwise provide in the part configurations involved.

While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. 

1. A method for mechanically connecting metallic parts to each other, comprising: rotating first and second metallic parts with each other about a central axis with the first metallic part having an outer locking formation; and rotating a flow forming tool about a tool axis at a location spaced radially outward from the central axis; and moving the rotating flow forming tool axially along the central axis to flow form the second metallic part around the first metallic part in a mechanically interlocking relationship with the outer locking formation of the first metallic part.
 2. A metallic part flow forming connecting method as in claim 1 wherein the outer locking formation of the first mechanical part includes circumferentially spaced locking projections about which the second metallic part is flow formed to provide both circumferential and axial mechanical interlocking of the parts to each other.
 3. A metallic part flow forming connecting method as in claim 1 wherein the first and second metallic parts are selected from the group consisting of: parts made of different types of metals; parts having different heat treatments; parts having different compositions; parts made from blanks made by different processes; and combinations thereof.
 4. A metallic part flow forming connecting method as in claim 1 wherein a plurality of flow forming tools are rotated about associated axes at a location spaced radially outward from the central axis, and the rotating flow forming tools being moved together axially along the central axis to provide the flow forming of the second metallic part around the first metallic part in its mechanically interlocking relationship with the outer locking formation of the first metallic part.
 5. A method for mechanically connecting metallic parts to each other, comprising: initially forming a first metallic part with an outer locking formation including locking projections spaced circumferentially and extending outwardly from a central axis; rotating the first metallic part and a second metallic part with each other about the central axis; rotating a flow forming tool about a tool axis at a location spaced radially outward from the central axis; and moving the rotating flow forming tool axially along the central axis to flow form the second metallic part around the circumferentially spaced locking projections of the outer locking formation of the first metallic part in an axial and rotationally mechanically interlocking relationship.
 6. Apparatus for mechanically connecting metallic parts to each other, comprising: a spindle for rotatably mounting first and second metallic parts about a central axis with the first metallic part having an outer locking formation; and a flow former including at least one rotary flow forming tool mounted for rotation about a tool axis at a location spaced radially outward from the central axis; and the flow forming tool being mounted for axial movement along the central axis during the rotation thereof to flow form the second metallic part around the first metallic part in a mechanically interlocking relationship with the outer locking formation of the first metallic part.
 7. Apparatus for mechanically connecting metallic parts as in claim 6 wherein the spindle includes a mandrel and a tailstock between which the first and second metallic parts are axially clamped and supported for the rotation about the central axis.
 8. Apparatus for mechanically connecting metallic parts as in claim 6 wherein the flow former includes a plurality of flow forming tools that are rotated about associated axes at a location spaced radially outward from the central axis and that are moved axially along the central axis to provide the flow forming of the second metallic part around the first metallic part.
 9. A metallic part assembly comprising: a first metallic part having a central axis and an outer locking formation including locking projections extending outwardly from and spaced about the central axis; and a second metallic part that is flow formed around the outer locking formation of the first metallic part and located on opposite axial sides and circumferentially between the locking projections so as to mechanically interlock the first and second metallic parts to each other.
 10. A metallic part assembly as in claim 9 wherein the first and second metallic parts are selected from the group consisting of: parts made of different types of metals; parts having different heat treatments; parts having different compositions; parts made from blanks made by different processes; and combinations thereof. 